Cleaning device and method

ABSTRACT

A cleaning kit for use in cleaning surfaces in clean rooms, semiconductor fabrication plants, pharmaceutical manufacturing facilities, etc. A stack of extremely clean wipers is packaged together with a container of cleaning fluid in a liquid-tight outer container. The outer container is vacuum-sealed. The kit is stored until just before it is to be used. Fluid is released from the inner container into the wipers, preferably by the use of a puncturing device operable to puncture one of the walls of the inner container by the application of pressure in a limited area on the outside of the outer container. The cleaning liquid is allowed to soak into the wipers, and the wipers are removed from the outer container for use.

This is a division of U.S. patent application Ser. No. 08/803,781, filedon Feb. 24, 1997, now U.S. Pat. No. 5,814,159, which is a continuationof application Ser. No. 08/527,153, filed Sep. 12, 1995, abandoned,which is a continuation-in-part of application Ser. No. 08/402,113 filedMar. 10, 1995 abandoned.

This invention relates to cleaning devices and methods, and particularlyto such devices and methods used in cleaning "clean rooms",semiconductor fabrication plants, semiconductor fabrication plants,pharmaceutical manufacturing facilities, and other cleaning applicationsand environments where extreme cleanliness must be maintained.

The requirements for maintaining cleanliness in semiconductorfabrication clean rooms, pharmaceutical manufacturing facilities andsimilar facilities are stringent.

In semiconductor fabrication clean rooms, surfaces frequently must bewiped with an exceptionally clean wiper and cleaning solution in orderto prevent contamination. The contamination which is to be controlledoften is called "microcontamination" because it consists of smallphysical contaminants, such as particulate matter of a size between thatof bacteria and viruses, and chemical contaminants in very lowconcentrations, typically measured in parts per million or parts perbillion.

The contaminants usually are of three types; particles, ions and"extractables", which are impurities leached from the fibers of thewiper.

Loose particles 100 micrometers and smaller in size are an anathema toobtaining high production yields and reliable semiconductor devices.Therefore, wipers and cleaning materials used in such clean rooms shouldemit as small a number of loose particles as possible.

Similarly, ions and "extractables" interfere with the exacting processof semiconductor manufacturing, and their quantities are to beminimized.

In the past, such requirements have been met by the provision ofspecially fabricated cloths designed to emit very few loose particles,while maintaining structural integrity when wetted with cleaningsolution and being used to wipe the surfaces to be cleaned.

Typically, such wipers have been packaged in sealed containers such asflexible plastic bags, which can be opened, a wiper withdrawn, and thebag resealed. Then, the cleaning solution, kept in a separate container,is applied to the wiper, and the wiper is used.

A problem with the foregoing is that substantial quantities of sometimesdangerous chemical solvents used as cleaning fluids must be stored andapplied to the wipers. This can result in accidents or workingconditions deleterious to the health of the workers.

Another problem lies in the fact that when workers apply cleaning fluidsfrom separate containers to dry wiper cloths, the amount of cleaningfluid used often is either too little or too much, which can result inineffective cleaning, or oversaturation and waste.

In response to the latter problems, pre-saturated wipers have beendeveloped and sold successfully. The wipers are pre-loaded with varyingamounts of cleaning solutions, and packaged in a re-sealable plastic baguntil needed. Then, the bag is opened, the wiper or wipers withdrawn,and the bag is re-closed. This is repeated until the bag is empty.

In accordance with the present invention, the inventors have recognizedthat bags of presaturated wipers often may be stored for prolongedperiods, such as months or even years before use. During that time, thecleaning liquid and the wiper material are in intimate contact with oneanother. It is believed that this often leads to a degradation of thefibers of the wiper material such that the quantity of contaminantsreleased by the wiper when used is substantially higher than when thewipers are first packaged. It is believed that the bonds holding theparticles to the fibers are loosened, and the releasable ions andextractables are increased by prolonged contact between the cleaningsolutions and the wipers.

In addition, where adhesives are used to fasten various parts of plasticpackaging together, such as in the re-closable seal of some wiperpackages, the adhesive may deteriorate due to prolonged contact with thecleaning liquid. The inventors have recognized that this limits thechoice of adhesives that can be used.

In the cleaning of pharmaceutical manufacturing and other medicalfacilities, one of the problems lies in maintaining the effectiveness ofa biocide contained in presaturated wipers. The applicants haverecognized that the effectiveness of the biocide may deteriorate due toprolonged contact with the wiper material.

It is an object of the present invention to solve or alleviate theforegoing problems. In particular, it is desired to provide extremelyclean cleaning applicators or wipers which are loaded with a cleaningfluid just prior to use without the risk of applying the cleaning fluidfrom separate containers stored on site.

In particular, it is desired to provide such wipers and methods of usingthe wipers for cleaning clean rooms and pharmaceutical manufacturingfacilities, etc., in which the cleaning fluids are applied to the wipersat a time just prior to their use so as to prevent prolonged contactbetween the wipers and the fluids.

In accordance with the present invention, the foregoing objectives aremet by the provision of a cleaning kit comprising a liquid-tight outercontainer containing at least one, and, preferably, a plurality ofcleaning applicators or wipers and a cleaning liquid in an innercontainer. Preferably, both the inner and outer containers are plasticbags, and the kit includes a substantial number of wipers. Means areprovided for opening the inner bag while it is inside of the outer bagto release its contents for absorption by the wipers. Preferably, theinner bag contains a puncturing device operable by hand pressure fromoutside.

In the cleaning method using the kit, the kit is stored with thecleaning liquid sealed in the inner container until just prior to use.To apply cleaning liquid to the wipers, pressure is applied, preferablyby hand, to the inner container through the material of the outercontainer to puncture the inner container and release cleaning liquidonto the wipers. The wipers then are allowed to absorb the liquid, thepackage is opened, and one or more wipers are removed and used to cleansurfaces.

It is preferable that the outer bag be re-closable so as to protectwipers remaining in the bag from contamination and to minimizeevaporation of the cleaning liquid.

This kit and method make it possible to greatly reduce the amount oftime that the cleaning fluid and wiper materials remain in contact withone another, thus reducing the opportunity for additional generation ofcontaminants, or degeneration of the cleaning fluid.

In accordance with another aspect of the invention, a unique cleaningliquid container is provided. The liquid container preferably is aflexible plastic bag made of material resistant to attack by thecleaning liquid contained in the bag. The bag contains a puncturingdevice which punctures the wall of the bag when pressure is applied byhand. This allows the discharge of cleaning liquid from the bag to bedirected to the most effective location for quick absorption by thewipers.

Preferably, the puncturing device comprises a flat plastic plate with aplurality of projections or spikes extending from one side of the plate.The plate is made of a plastic material such as polyethylene which isimpervious to most cleaning liquids, and the projections or spikes aredistributed over a substantial area so as to maximize the rate ofabsorption of the liquid into a stack of wipers.

Preferably, the puncture device is made substantially smaller than thestack of wipers and is located inwardly from the outer edges of thewiper stack to prevent the pressure applied at the edges of the packageduring the ordinary gripping of it from accidentally puncturing theliquid container. The outer bag is vacuum-sealed to hold the inner bagsecurely at a central location on the wiper stack. The vacuum sealingalso pressurizes the inner bag and discharges the liquid from itrelatively quickly.

The likelihood of accidental puncture of the liquid container also isreduced by the fact that pressure applied over a broad area of thecontainer is not effective to cause puncturing. Pressure applied over arelatively small area, by means of a knuckle or other blunt instrument,will cause the desired puncture. In addition, the puncture device isbuoyant in the cleaning liquid and its spikes normally do not engage thebottom of the container.

The foregoing and other objects and advantages of the invention will beset forth in or apparent from the following description and drawings.

IN THE DRAWINGS

FIG. 1 is a perspective, partially broken-away view of a cleaning kitconstructed in accordance with the present invention;

FIG. 2 is a perspective view of the cleaning kit shown in FIG. 1, withthe kit inverted;

FIG. 3 is a cross-sectional, partially schematic view taken along line3--3 of FIG. 1;

FIG. 4 is a plan view of the contents of the outer container of the kitshown in FIG. 1;

FIG. 5 is a perspective view of a portion of an alternative embodimentof the invention;

FIG. 6 is a perspective view of another embodiment of the invention;

FIG. 7 is a cross-sectional view taken along line 7--7 of FIG. 6;

FIG. 8 is a bottom plan view of a portion of the device shown in FIGS. 6and 7;

FIG. 9 is a perspective view partially broken-away, of anotherembodiment of the cleaning kit of the invention;

FIG. 10 is a cross-sectional view taken along line 10--10 of FIG. 1;

FIG. 11 is a top plan view of a portion of the kit shown in FIGS. 9 and10; and

FIG. 12 is an enlarged elevation view of one of the spikes of theperforation plate shown in FIGS. 9-12.

CLEANING KIT

FIG. 1 shows a cleaning kit 10 constructed in accordance with thepresent invention.

The kit 10 includes an outer container 12, which is partially brokenaway, a stack 14 of rectangular applicators or wipers, and a frangiblecontainer 16 of cleaning liquid resting on top of the wipers.

The outer container 12 is a flexible plastic bag made of a materialresistant to attack by the cleaning liquid contained in the container16. It is air-tight and liquid-tight. It is formed by a first sheet 18forming a bottom panel on one side, and a second sheet 20 forming a toppanel on the opposite side. The sheets 18 and 20 are made of plastic andare adhered together along a seam 26 to form an air-tight andliquid-tight container.

As it is shown in FIG. 2, in which the kit of FIG. 1 has been inverted,the top panel 20 of the outer container 12 has an elongated outletopening 22 near one edge. The outlet opening 22 normally is closed by aplastic strip 24 coated with a pressure-sensitive adhesive, except atone end 25 where a tab is left uncoated and free to be grasped by theuser. To open the outlet opening, the user pulls on the tab 25, peelsback the strip 24, withdraws one or more of the wipers 14 through theopening 22, and re-closes the opening by pressing down on the flap 24,thereby protecting the remaining wipers from contamination.

Preferably, the bag 12 has most of the air evacuated from it so that thematerial of the bag makes close contact with the stack of wipers 14 andthe container 16. This is believed to facilitate the bursting of thefrangible container, and to hold it in the preferred position relativeto the wipers 14.

FRANGIBLE CONTAINER

The frangible container 16 is shown in FIGS. 3 and 4, as well as inFIG. 1. Preferably, it comprises two sheets of flexible plastic materialsealed together along edges 36, 38, 40 and 42 (FIG. 4), as well as alonga center strip 44. This forms two separate compartments 28 and 30, eachcomprising, in essence, a separate frangible bag.

In accordance with one aspect of the present invention, each of the bagshas a weakened area in which it is designed to break when pressure isapplied to it. This is used to direct the flow of the cleaning liquid tothe wipers in a location which minimizes the time required to dampen thewipers.

Preferably, the seams 36, 38, 40, 42 and 44 are formed using aheat-sensitive adhesive, and the weakened area is provided by weakeningthe adhesion between the plastic sheets at two zones 46 and 48, one foreach compartment. The zones 46 and 48 are located approximately on thelateral centerline 66 of the wiper stack 14, as shown in FIG. 4.

Each weakened zone 46 and 48 is formed by heating the adhesive formingthe seams in those zones differently from the remainder of the seams ofthe bag 16. For example, zones 46 and 48 are heated at a temperatureand/or pressure or for a time which is lower than for the remainder ofthe seams.

Alternatively, the width of the seam or the adhesive coating in eachzone 46 and 48 can be reduced relative to the remainder of the seams toprovide the desired weakening.

It is desired to set the strength of the weakened areas 46 and 48 at alevel sufficient to withstand the application of pressure to the tops ofthe bags 28 and 30 over a relatively broad surface area, but break apartunder pressure applied over a relatively narrow area.

In accordance with one aspect of the present invention, each bag isburst relatively easily by the application of pressure in a relativelysmall area 52 (see FIGS. 3 and 4). Sufficient pressure can be applied byhand. This can be done by placing the kit 10 on a flat surface 68, suchas a table, with the top panel 20 facing downwardly. The bags 28 and 30bulge upwardly as shown in FIG. 3. Each contains a quantity 32 or 34 ofcleaning liquid.

By simply pressing downwardly with the knuckle 50 of one finger in thearea 52, sufficient pressure can be developed to burst the seam in zone46 or 48, creating a gap 58 (FIG. 3) in the seam which allows thedischarge of fluid from the container 30 to a location 54.

FIG. 3 shows the area 52 depressed by the knuckle 50 as if it were onthe lateral centerline 66 of the kit. Actually, as it is shown in FIG.4, the area 52 is located near one end of the bag 30. This illustratesthe feature of the invention in which it does not matter where on thebag 28 or 30 the pressure is applied; the bag will burst at the properlocation anyway.

In order to illustrate the resistance of each bag 28 and 30 to unwantedbreakage, it has been found that many people cannot break the bag byapplying pressure with the palm of the hand, but can break it easilywhen pressure is applied by means of one knuckle, or some other bluntinstrument which concentrates the force in a small area withoutpuncturing the bag.

From the location 54, the liquid escaping from the bag 30 is absorbedand spreads from the zone 54 downwardly and to the sides, as indicatedby the arrows in FIGS. 3 and 4, until the liquid has moistened theentire stack of wipers.

Similarly, applying pressure over a relatively small area of the surfaceof the container 28 will cause the container to burst at the seam area48 and will cause the liquid 32 to be discharged into the area 56, fromwhich it spreads downwardly and sideways to help load the cleaningliquid into the wipers.

Preferably, the areas 54 and 56 of fluid discharge are located on thelateral centerline 66 of the wiper stack, as shown in FIG. 4, and near aline 62 or 64 which is approximately mid-way between the verticalcenterline 60 of the wiper stack (FIG. 3), and the right and left edgesof the stack. This insures relatively rapid distribution of the liquidinto the wipers.

It should be understood that liquid might emerge from the openings inthe bags 28 and 30 in a jet and thus might run down the sides of theouter bag 12. This would alter the flow pattern of the liquid as it isabsorbed, but may speed the absorption process.

After the bags 28 and 30 have been burst, the user simply allows the kit10 to rest in the position shown in FIG. 3 for a certain period of timeuntil the liquid has been distributed throughout the stack of wipers.

Then, the user inverts the package to the position shown in FIG. 2,pulls back the strip 24 to expose the edges of the wiper stack throughthe outlet hole 22, removes one or more wipers for use, and replaces theadhesive flap over the opening 22 to protect the remaining wipers.

Advantageously, because the outer bag 12 has been inverted from theposition shown in FIG. 1, the empty cleaning liquid bags 28 and 30 noware on the bottom of the wiper stack 14 where they do not interfere withthe removal of the wipers from the package.

This arrangement has further advantages when it is time to dispose ofthe packaging. Since the empty bags 28 and 30 are still in the outercontainer 12, it is a simple matter to throw away all of the packagessimultaneously, without any handling of the bags 28 and 30.

As it has been stated above, by evacuating most of the air from theouter bag 12, the bags 28 and 30 are held in a desired position relativeto the stack of wipers 14. Alternatively, an adhesive can be applied tothe outer surfaces of the bags 28 and 30 which makes contact with theinside of the wall 18 of the outer bag so as to hold the bags 28 and 30against shifting and insure their proper location when broken.

ALTERNATIVE EMBODIMENTS

The rate of absorption of cleaning liquid can be increased even furtherby increasing the number of frangible bags used, thus further reducingthe distance required for the liquid to travel in dampening all of thewipers.

For example, four bags, each with its own weakened area, can be used inplace of the two bags 28 and 30. The fluid release points then could belocated at a spacing between the top and bottom borders of the stack 14,shown in FIG. 4, like that used between the side borders, as shown inFIG. 3. That is, two release points could be midway between the lateralcenterline 66 and the upper edge, and two midway between the centerline66 and the bottom edge of the stack.

FIG. 5 shows an alternative construction for the bags 28 and 30. Insteadof using two separate sheets of plastic, only one is used, together withthe sheet 18 forming the bottom wall of the outer bag 12. This savesplastic material, and ensures that the bags will be secured in placerelative to the wipers so as to assure proper distribution of the liquidinto the wipers.

In addition, the outlines of the bags will be more visible to the userbecause the adhesive forming the seams 36, 38, 40, 42, and 44 willcreate faint outlines on the outer surface of the bottom 18 of the outerbag.

Preferably, the bags 28 and 30 are formed as pockets, with one open edgefor filling, before the sheet 1 is attached to the sheet 20 to form thebag 12. The pockets are filled and sealed shut, and the sheet 18 isattached to the sheet 20 to complete the bag 12.

In order to make the frangible bags more visible to the user, the bottomwall 18 of the outer bag 12 can be made transparent.

FIGS. 6 through 8 show another alternative embodiment of the invention.

Shown in FIGS. 6 and 7 is a kit 70, similar to that shown in theprevious Figures of the drawings. However, the kit has a different meansfor releasing the cleaning liquid from the internal bag or bags to loadthe cleaning liquid into a stack 14 of wipers.

In the embodiment shown in FIGS. 6 and 7, an elongated re-closableoutlet opening 72 is provided along one edge of the side panel 18 of theouter container 12. This is provided instead of the opening in the othersurface 20 of the bag shown in FIG. 2.

The inner cleaning solution-containing bag is formed by a perforatedplastic panel 78 which is secured at seams 80 and 82 at its edges to thepanel 18 of the outer bag, in the manner shown in FIG. 5. The panel 78has a plurality of relatively small holes 86 spaced over a large portionof its surface.

An adhesive sealing strip 88 covers the holes 86 and prevents liquid 84from leaking out of the inner container until it is desired to releasethe liquid.

The strip 88 is coated with adhesive only in a certain area 98 (FIG. 8).Areas 90, 96 and 92 are not coated with adhesive. The uncoated stripportion is folded at 90, and the end of the strip 92 extends slightlyoutwardly from the stack of wipers, as shown in FIG. 7. By this means,the end 92 can be gripped by a user to pull the adhesive strip in thedirection indicated by the arrow 94 in FIG. 8 to peel it away from thebottom of the liquid container and release the liquid through the holes86 to be absorbed by the wipers 14.

Due to the numerous holes 86, the liquid 84 is distributed and dispensedrelatively quickly into the wiper stack. Therefore, absorption of theliquid by the wipers is relatively rapid. After the relatively shortperiod of time required for the cleaning liquid to soak into the wipers,the wipers can be removed through the opening 72 for use. Thereafter,the opening 72 can be re-closed by pressing the adhesive strip 74 down,in the same manner as the strip 24 shown in FIG. 2.

The liquid-containing bag is not in the way of the removal of wipersafter its use because it is integral with the upper panel 18 of theouter container 12 and is no more of an impediment to removal of thewipers than the panel 18 itself would be.

It should be understood that, as it is shown in FIG. 7, the surfaces 96,78, and the upper surface of the wiper stack 14 are shown separated, forthe sake of clarity in the drawings. Actually, they would be pressedtogether and the kit 70 would be somewhat thinner than shown in FIG. 7.

If it is desired to separate the single inner container into multiplecontainers, in a manner similar to the embodiments shown in FIGS. 1through 5, the separate containers can be aligned with theirlongitudinal axes parallel to the direction of the arrow 94. Then, aseparate adhesive strip can be provided for each separate pouch. Thesenarrower adhesive strips may be somewhat easier to remove than thesingle wide strip.

In another embodiment, a tear strip (not shown) can be used to tear openthe bottom of a pouch similar to that shown in FIGS. 6-8. The tear striphas an end available for gripping, like the end 92 shown in FIGS. 6-8.

PREFERRED EMBODIMENT

FIGS. 9 through 12 show the preferred embodiment of the invention.

The cleaning kit 101 shown in FIGS. 9 and 10 is the same as the cleaningkit 10 shown in FIG. 1, except the internal bag or container 100 is notfrangible. Instead, the bag 100 is an ordinary plastic bag with aconventional heat seal 103 all the way around. The bag 100 contains apuncturing device 102, in addition to cleaning fluid 32 (see FIG. 10).

As it is shown in FIGS. 9 through 11, the puncturing device 102comprises a plastic plate having a plurality of projections or spikes106 extending from one side of the plate. FIG. 12 provides an enlargedview of one of the spikes 106. Each spike 106 has a conical shape and ispointed at its end. The spikes 106 are arranged in a circle spacedoutwardly from the center of the plate. The edges of the plate arescalloped as shown at 104.

The puncturing device 102 preferably is molded out of a cleaningliquid-resistant plastic material such as polyethylene.

The kit 101 is used in the following manner. The outer container 18 witha stack of wipers 14 in it is laid on a flat surface 68 (FIG. 10). Thepuncturing device 102 is actuated by the user applying pressure in alimited area such as by pressing a finger 108 or a thumb downwardly onthe outer package at about the center of the package. This appliesdownward pressure on the puncturing plate 102, and the spikes 106 piercethe bottom wall of the bag 100 and allow the liquid 32 to flow into thewipers in the areas 100 (FIG. 10) and be absorbed into the wipers.

The kit 101 is protected against accidental puncture by making the bag100 substantially smaller than the wipers 14, and by positioning thespikes 106 inwardly from the outer edges of the plate. By this means, asubstantial distance is created between the edge of the outer container18 and the edge of the puncturing plate. Thus, when a person grasps thepackage at the edge, the thumb will not accidentally depress the plateand cause an unwanted puncture.

It is preferred that the outer bag 18 be vacuum sealed. This holds theinner bag 100 in a central location on the stack of wipers 14.

Unwanted accidental puncture also is prevented by the fact that pressuresufficient to cause a puncture is not transmitted within the bag by theapplication of pressure over a large portion of the surface area of thebag 100. However, adequate pressure is provided when it is applied bymeans of a knuckle, finger, thumb, or blunt instrument. Thus, when thekits are stacked on top of one another during shipment, accidentalpunctures are not likely to occur.

The puncturing device 102 preferably is buoyant within the liquid 32contained in the bag 100. Thus, it normally floats above the bottom wallof the bag 100 when the kit 101 is positioned as shown in FIG. 10. Thisis believed to help to prevent accidental puncture.

The shape of the plate forming the puncture device can be varied withoutchanging the nature of the invention. For example, the disc from whichthe spikes 106 extend can have a generally circular shape as indicatedby dashed line 107 in FIG. 11. A square or other geometric shape is alsofeasible.

In a cleaning kit which has been built and successfully tested, the bag100 was a square bag seven and one-half inches on each side; the outercontainer 18 was a square bag eleven and one-half inches on each side;and the maximum diameter of the puncture plate was five and one-halfinches. The thickness of the plate was 0.08 inches.

Referring to FIG. 12, the length L of each of the spikes 106 wasapproximately 0.35 inch, and the width W of each spike at its base wasapproximately 0.25 inch. The length of each spike is minimized to lessenthe chances of accidental puncture, without detracting substantiallyfrom the ability of the spikes to puncture the bag 100.

As it has been stated above, the outer bag 18 preferably is vacuumsealed; that is, it is at least partially evacuated of air. This hasseveral advantages when used with the present invention.

One advantage of vacuum sealing is that the bag 100 is held tightlyagainst the stack in a central location so that it does not shift fromone side of the package to the other during shipping and handling. Thisprevents the puncturing disc from coming too close to any of the edgesof the package and, thus, helps to avoid accidental puncture.

Vacuum sealing has another advantage. This is that the cleaning liquid32 in the bag 100 is pressurized by the vacuum so that the liquidpassing through the openings made by the spikes 106 puncturing thebottom wall of the bag 100 flows through the holes much faster than itwould otherwise. This makes the absorption of the liquid into the wipers14 much faster than if the vacuum were not applied.

Also, vacuum sealing holds the wipers tightly against one another sothat they will not rub against one another. This prevents the increaseof the number of loose particles which might be developed in the wipersby rubbing them against one another.

The bag 100 is advantageously made with ordinary heat-sealing proceduresand is relatively low cost to make. The puncturing device also isrelatively inexpensive and is biodegradable, as are other materials inthe kit.

Thus, the kit 101 is relatively inexpensive to make and easy to use. Itallows the wetting of the wipers to be delayed until just prior to theuse of the wipers, thus preventing the deleterious effects of prolongedcontact between the cleaning liquid and the wipers.

WIPERS

The term "applicator" or "wiper", as used in this specification, isintended to mean a cleaning fabric, suitable for use in cleaningsurfaces in clean rooms and the like.

Such applicators or wipers are distinguished from tissues and similarmaterials in that they are extremely clean, and in that they have arelatively high degree of wet strength and structural integrity whenused to wipe surfaces while dampened or saturated with cleaning liquids.

As it is well known, a certain minimum amount of liquid must be appliedto a stack of wipers in order for the liquid to be distributedthroughout all of the wipers without dry spots. This minimum amountvaries depending upon the type of wiper used, the type of cleaning fluidused, and other factors. However, a typical level might be 20% to 40% ofthe amount required for full saturation.

Typically, when clean room wipers are used in wet cleaning applications,the degree of saturation is substantially below 100%, usually in therange between 40% and 70%, so that the wiper releases solvent onto thesurface when it is pressed against the surface, and re-absorbs theliquid when pressure is released so as to leave no substantial residualliquid on the surface.

In contrast, in pharmaceutical manufacturing facilities, it often isdesired to leave a coating of liquid biocide on the surface so as toprovide maximum sterilization. Thus, such wipers often are saturatedcompletely with a biocide-containing cleaning substance.

The total quantity of cleaning liquid in the frangible bags 28 and 30 isat least equal to the minimum needed to moisten all the wipers, and canbe in excess of 100% of the amount needed for full saturation.

Cleaning fabrics used in sensitive areas, such as semiconductorfabrication clean rooms and pharmaceutical manufacturing facilities, arecarefully selected for characteristics such as particle emission levels,levels of ionic material, adsorptiveness, resistance to attack ordegradation by cleaning materials used, and lack of attack by ordegradation of biocides.

Some of the wiper fabrics which have been successfully used in suchapplications include knitted, woven and non-woven fabrics such as thefollowing:

1. 100% polyester or nylon, preferably knitted from continuous filamentyarn. Typical products are sold under the trademarks "AlphaWipe";"AlphaSorb"; and "Alpha10"; or "MiracleWipe" by the Texwipe Company,Upper Saddle River, N.J. Woven polyester or nylon fabrics also can beused.

Some of such fabrics are sealed along the edges, in the manner indicatedschematically in FIG. 4 at 70, and as more fully described in U.S. Pat.No. 4,888,229.

2. 100% spun bond polypropylene. The fibers of these fabrics arearranged randomly and are bound together by heat or chemical action. Atypical product using this construction is sold under the trademark"PolySat" by the Texwipe Company.

3. 55% cellulose and 45% polyester fiber or 100% polyester boundtogether by hydroentanglement. A typical product is the Texwipe"TechniCloth" product.

4. 100% polyurethane foam.

5. Other fabrics made of rayon, acrylic, abaca, (e.g., "M-Wipe" wiperssold by Texwipe), hemp, cotton, etc.

CLEANING FLUIDS

Cleaning fluids suitable for use in the invention include virtually anysubstance capable of cleaning. Some of the cleaning substances which canbe used in this invention and which sometimes cause problems due toprolonged contact with wiper materials are listed below:

1. Deionized water. Deionized water is a more aggressive solvent thanordinary water. Furthermore, there is a danger of bacterial growth ifthe water remains in prolonged contact with wiper materials.

A bactericide can be added to the water. However, it sometimes loses iseffectiveness due to prolonged contact with the wiper material. It alsomay introduce contamination into the cleaning liquid.

2. A biocide and water.

3. A mixture of water and alcohol, isopropyl alcohol ("IPA") inparticular. Solutions of 6% or less IPA to 100% IPA can be used.

4. A mixture of water and glycol ether, such as propylene glycol ether.The percentage of active ingredient can vary from 3% to 100%, but thenormal range is 3% to 6%. A typical product is sold under the trademark"TexPure" by Texwipe.

5. Acetone--100% pure. Acetone is very volatile and can attack someadhesives.

6. A mixture of water and detergent and/or surfactant with or without abiocide.

7. For cleaning optical surfaces, a glass cleaner containing ammonia orother basic solution, such as sodium hydroxide.

8. Hydrogen peroxide plus water. A 35% solution usually is used,together with a stabilizer.

9. Various organic solvents.

10. Terpenes. Terpenes tend to dissolve the adhesive seal on the outsidecontainer when it is subjected to prolonged contact, thus limiting thechoices of adhesive when manufacturing the product.

11. Acids (weak solutions).

12. A solution of a bleach such as sodium hypochlorite and water.

BAG MATERIALS

The material of which both the frangible bag 16 and the outer bag 12 aremade should be resistant to attack to the cleaning fluid in the kit. Forexample, polypropylene is resistant to a wide variety of cleaningsolvents, and thus is a preferred material. Polyethylene similarly is asuitable material.

Also, Teflon (polytetrafluoroethylene) can be used where its greaterexpense is justified.

NUMBER OF WIPERS IN A KIT

The thickness of the stack 14 of wipers in a particular kit can varyfrom one up to a very substantial number. However, the larger the numberof wipers in a kit, the longer it will take for the wipers to absorb thecleaning fluid. Therefore, the number to be used in a particular kitdepends upon the cleaning fluid, the wipers and the length of time theuser is willing to wait after releasing the liquid before the wipers canbe used.

Typically, with most of the wipers specifically identified above, a kitcontaining 50 wipers would be considered to be most widely acceptable.In clean room use, such a quantity typically will last from one day totwo weeks. However, up to several hundred wipers could be placed in asingle kit, if desired.

With around 50 wipers and typical cleaning fluids, the waiting time forfull absorption of the cleaning fluid is of the order of magnitude of 5minutes. Times up to 20 minutes might be required in certaincircumstances.

Of course, if a smaller number of wipers is used, the absorption can bevery fast.

For example, a kit containing a relatively small number of, say, 1 to 5wipers could be used as an emergency kit. The kit could be activatedvery quickly because the small number of wipers would not require a longtime to become moistened.

The speed of readying the wipers for use can be increased even furtherby increasing the quantity of liquid distributed to the wipers. Althoughthe wipers might be somewhat overloaded with cleaning fluid, that couldbe acceptable on a temporary basis, in exchange for faster readiness foruse in emergencies.

It should be understood that various other means of releasing the liquidfrom the internal container can be devised without departing from thebasic concept of the present invention.

The above description of the invention is intended to be illustrativeand not limiting. Various changes or modifications in the embodimentsdescribed may occur to those skilled in the art. These can be madewithout departing from the spirit or scope of the invention.

We claim:
 1. A cleaning kit, said kit comprising, in combination, afirst liquid-tight container, at least one absorbent flat ultra-cleanwiping cloth in said first container, a second liquid-tight containerpositioned within said first container on said wiping cloth, a cleaningliquid in said second container, said second container being openablewhile it is located in said first container to release said liquid fromsaid second container to be absorbed by said wiping cloth, and apuncturing device located in said second container and positioned topuncture a wall of said second container to release said cleaning liquidin response to actuation from the outside of said second container.
 2. Acleaning kit as in claim 1 in which said puncturing device comprises aflat plate with a plurality of piercing projections extending therefromtowards said wiping cloth.
 3. A cleaning kit as in claim 1 including aplurality of said wiping cloths, in which the material of which each ofsaid containers is made is resistant to attack by said cleaning liquid,and in which said first container has a re-closable opening throughwhich said wiping cloths can be removed.
 4. A cleaning kit as in claim 1in which said wiping cloth is a wiper for use in clean rooms requiringthe use of wipers producing very small quantities of contaminants inuse, and said cleaning liquid can increase the amount of contaminantsproduced by said applicator when kept in prolonged contact with saidwiper.
 5. A cleaning kit as in claim 1 in which said cleaning liquid isselected from the group consisting of: de-ionized water; alcohol; amixture of water and alcohol; acetone; a mixture of water and glycolether; a mixture of water and a biocide; a mixture of water, detergentand/or surfactant, with or without a biocide; a mixture of hydrogenperoxide and water; terpene; a mixture of ammonia and water; and amixture of bleach and water.
 6. A cleaning kit, said kit comprising, incombination, a first liquid-tight container, at least one cleaningapplicators in said first container, a second liquid-tight containerwithin said first container, a cleaning liquid in said second container,said second container being openable while it is located in said firstcontainer to release said liquid from said second container to beabsorbed by said applicator, and a puncturing device located in saidsecond container and positioned to puncture a wall of said secondcontainer to release said cleaning liquid in response to actuation fromthe outside of said second container, in which said applicators areclean-room wipers, said puncturing device comprising a flat plate with aplurality of piercing projections extending therefrom, said plate beingsubstantially smaller than said applicators, said piercing projectionsbeing spaced apart from one another and extending over a substantialarea of said plate, said plate being depressible by the application ofpressure in a small area on the outside of said first container.
 7. Acleaning kit as in claim 1 in which one of said cleaning liquids andsaid wiping cloth is subject to deterioration due to prolonged contactwith the other, and said wiping cloth is made of a fabric selected fromthe group consisting of knitted fabrics; woven fabrics; non-wovenfabrics; including spunbond fabrics; hydroentangled fabrics; and foam.8. A cleaning kit as in claim 1 in which said first container is atleast partially evacuated.
 9. A cleaning kit as in claim 2 in which saidplate is made of a material resistant to chemical attack by saidcleaning liquid, and which is buoyant in said liquid.
 10. A cleaning kitcomprising, in combination, a plurality of clean room wipers, eachproducing relatively low loose particle counts and being suitable foruse in semiconductor fabrication clean rooms, a plastic bag of cleaningfluid containing a solvent, a solvent-resistant, liquid-tight outercontainer, said bag containing a puncturing device actuatable fromoutside said outer container, said bag resting atop of said wipers whensaid outer container is resting on a surface with the bottom wall ofsaid outer container up, said outer bag having a re-closable opening ina wall of said outer bag other than said bottom wall.
 11. A cleaning kitas in claim 10 including a flap normally covering said opening andbearing a pressure-sensitive adhesive for use in re-covering saidopening after removal of a wiper from said outer bag, said flap beingreadily removed and replaced when said outer bag rests on said bottomwall.
 12. A cleaning kit as in claim 10 in which said puncturing devicecomprises a flat plate with a plurality of spikes extending therefrom.13. A cleaning kit as in claim 10 in which said plastic bag is held inposition relative to said wipers by vacuum sealing said outer bag.
 14. Acleaning kit as in claim 10 in which said plastic bag is substantiallysmaller than said wipers.
 15. A flexible liquid container for use inselectively releasing a cleaning liquid in response to the applicationof pressure by hand, said container comprising a flexible bag made of aplastic material resistant to attack by said cleaning liquid, said baghaving a puncturing device comprising a support member with a pluralityof spikes extending g therefrom and being capable of being actuated byhand pressure from without said container to release said cleaningliquid, and a cleaning liquid contained within said bag said cleaningliquid containing a material selected from the group consisting of asolvent and a biocide.
 16. A container as in claim 15 in which said bagpuncturing device comprises a support member with a plurality of spikesextending therefrom.
 17. A container as in claim 15 in which saidsolvent is selected from the group consisting of de-ionized water,alcohol; a mixture of water and alcohol; acetone, a mixture of water andglycol ether; a mixture of water and a biocide; a mixture of water anddetergent and/or surfactant with or without a biocide; a mixture ofhydrogen peroxide and water; terpene; ammonia and water and bleach andwater and bleach water.